Need help with condensation problem during finishing.

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Forum topic by slooper posted 02-07-2009 10:19 PM 800 views 0 times favorited 4 replies Add to Favorites Watch
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37 posts in 3715 days

02-07-2009 10:19 PM

This morning I took my project outside to put a first coat of water born poly on. After the specified drying time I went to sand with 320 grip paper so I could apply the second coat and the poly peeled off like dry skin. I can’t seems to sand it smooth.

I noticed what I thought to be condensation during the application of the poly. I tried to brush if smooth but I guess that didn’t work. It is damp outside, so maybe I should have waited for a better day.

How can I fix this without sanding all the way down to the wood and re-staining? Anyone?


4 replies so far

View Scott Bryan's profile

Scott Bryan

27250 posts in 4059 days

#1 posted 02-07-2009 10:34 PM

Slooper, one thought that I had was the poly may not be cured out. In cooler weather it will take the finish longer to cure because basically you trying to let water evaporate. These type of finishes work best when applied at room temperature. Lower temperature and higher humidity will slow the drying process.

If this is the problem then trying to sand it when the finish is still curing will just gum up the sandpaper and end up making a mess of the finish. The solution is to wait longer or bring it inside and put some heat on it.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

View Al Killian's profile

Al Killian

273 posts in 3990 days

#2 posted 02-08-2009 08:05 AM

If it is damp outside, your poly might not dry. When you say damp, do you mean it was raining earleir? Is there a reason why you are putting it on outside? Being wb poly it should dry fairly quick inside if it is above 50.

-- Owner of custom millwork shop

View slooper's profile


37 posts in 3715 days

#3 posted 02-08-2009 07:38 PM

Thanks Scott, I brought it inside and waited nearly 10 hrs for the poly to dry. The second cote went on nicely late last night.

Al, no rain, just melting snow and cloud cover. I wait to do my finishing outside because I share the shop space with my office and don’t want to breath it while it dries and clear out. Overnight seems to be long enough to dry and clear out the air, so I’ll probably do finishing last thing of the day from now on, at least with water born poly.

View slooper's profile


37 posts in 3715 days

#4 posted 02-11-2009 10:30 PM

Turns out that the poly I was using is somehow incompatible with the stain. I was actually using two different kind of stains on the project to get a two-tone affect. Only with one of these stains does the poly bead up like water on a waxed car. Unfortunately, since the stain came in an unmarked can from my RV manufacturer, I can’t determine what kind of stain it actually is. I suspected it was an alcohol base since it dried much faster than oil base. Can anyone conceive of what mixtures of stans-polies would cause the poly to bead up?

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